Unreal Engine 4.9 Released!

I’m having difficulties with convertin 4.8 project to 4.9. I opened it as copy in 4.9, but it hangs at 98%, engine stops responding according to Task Manager and it’s like that for 5-10mins before I do ctrl-alt-del. It’s really simple project, small landscape with trees and BP for walking character. Any suggestions? Any way to debug/ logs?